1. Field of the Invention
The invention relates to a manufacturing method of an aqueous stabilized chlorine dioxide solution which is effective when used as a germicide, disinfectant or deodorant.
2. Description of the Prior Art
It is known that chlorine dioxide (ClO.sub.2) has an intensive oxidizing capability concerning functions of sterilizing, deodorizing, bleaching and the like. However, chlorine dioxide has such disadvantages that since it is originally a gas, it is hard to be stored while chlorine dioxide requires a gas generator in use.
As a typical gas generator, the apparatus is known which generates chlorine dioxide as a gas by utilizing the following reaction. ##STR1##
In the apparatus, sodium chlorite and sodium hypochlorite as starting materials are used in equivalent amounts on the basis of the above reaction, i.e., in a molar ratio of about 2:1.
However, absorbing the chlorine dioxide gas from such a gas generator in water does not provide an aqueous stabilized chlorine dioxide solution, since chlorine dioxide absorbed is easily dissociated in a short time.
In recent years, such a method has been realized as shown in U.S. Pat. No. 3,271,242 that generated chlorine dioxide is to be absorbed in an aqueous alkali solution (e.g., sodium percarbonate solution) to thereby be stabilized. Such an aqueous solution is generally called "a stabilized chlorine dioxide" and is commercially available.
However, the method essentially comprises a gas generating step and a gas absorbing step as aforementioned and therefore causes complexity. Further, the concentration of chlorine dioxide in the solution can not easily be controlled through the gas absorbing step. Furthermore, according to the experiments by the inventors of the present invention, the aqueous solution prepared by the method is insufficient in stability and some amount of chlorite ions dissociated from chlorine dioxide are frequently found therein.
Under the circumstances, the inventors have conducted various studies and have found the fact that an aqueous stabilized chlorine dioxide solution with excellent stability on chlorine dioxide can be obtained by an one-step method, i.e., by subjecting a small amount of an alkali metal hypochlorite to react with a specific excessive amount of an alkali metal chlorite in an aqueous medium having a specific pH.